Field of the Invention
This invention concerns a tool that is useful in drilling wells, particularly deep wells being drilled for oil and/or gas production. More specifically, it concerns a special tool that is useful in connection with so-called fishing operations. Such operations involve actions for loosening and thereafter recovering a so-called "fish", which may be any substantial amount of drilling pipe or other equipment which has become stuck in a hole and is worth recovering.
Description of the Prior Art
As used throughout this application the terms fish and fishing operations, deal with the common usage of these terms in connection with well drilling and particularly oil and/or gas wells of considerable depths where rotary drilling equipment and operations are employed. It has been found that during fishing operations a fish that is to be recovered is ordinarily latched with an overshot, and then a so-called string-shot is run down through the pipe that has the overshot at the lower end. The jarring effect of detonating the string shot may help loosen or, if necessary, sever the fish so that the latched portion may be withdrawn and so recovered. However, when during such a fishing operation the fish itself is found to be plugged, the string shot is not able to penetrate down inside the fish. And, consequently such conditions necessitate the withdrawing of the entire string of pipe to which the overshot is attached in order that a different tool may be connected in order to direct the string shot to the outside of the fish so that it may continue down in the annulus but outside of the stuck fish. Particularly in deep well operations, the additional so-called trip which involves pulling up the string of pipe and inserting the extra tool, requires very considerable time and effort. Consequently, provision of a tool according to this invention avoids such a trip and saves much effort and time in connection with a fishing operation.
It will be appreciated by those skilled in the art that many of the terms employed in describing the tools and procedures herein are well known in well drilling operations and thus are well understood by such skilled artisans.
There is a U.S. Pat. No. 2,558,227 to J. R. Yancey et al, issued June 26, 1951. However, that patent deals with structure for carrying out a sidewall core-taking procedure which means that a core bit may be directed from inside of a string of pipe or tubing out into the formation. It includes a special structure at the lower end for diverting the core bit. That structure has a diverting "deflector plate assembly" which provides a sloping surface that directs the lower end of the core-taking equipment out into the formation at that location. However, such structure is not relevant to the applicant's invention which includes a gate that may be positioned as part of the wall of the tool so as to leave the inside completely open.